Constant current circuit



July 5, 1949. a s. PURINGTON 2,475,050

CONSTANT cw! CIRCUIT Original Hind Oct. 10, 1944 Q mvzuron.

nrmwzr Patented July 5,1949

2,475,050 CONSTANT CURRENT CIRCUIT Ellison S. Purington, Gloucester, Mam, ani nor,

by mesne assipnments, to

o Corp ration of America, New York, N. Y., a corporation of Delaware Original application October 10, 1944, Serial No. 557,983. Divided and this application June 20, 1945, Serial No. 600,477

2 Claims. 1

This application is a division of my copending U. 8. application serial No. 557,983, filed October 10, 1944, entitled Intertube coupling circuit," assigned to the same assignee as the instant application.

This invention relates to a pulse operated relay circuit and has for an object to provide a circuit oi the above type having novel and improved operating characteristics.

The invention relates more specifically to a circuit responsive to the coincidental reception of a pair of pulses at difierent input terminals and is adapted for use in a system 01 the type shown in my copending application Ser. No. 537,799, filed May 29, 1944, new E'atent No. 2,449,819, for Radio control system, wherein pairs of pulses are transmitted over difierent channels in selected time sequences and are made available at the receiver in accordance with their sequence as coincidental pulses.

ln-one embodiment the present invention provides a relay circuit in which the coupling between a pulse amplifier tube and a relay tube is eirected throush a gaseous discharge tube which is normally non-conducting but becomes conducting in response to the received pulse. The relay tube becomes operative only when the intertube coupling path becomes conducting. The invention also provides a relay circuit in which the plate current remains substantially constant regardless of the stete oi operation oi the relay.

Although the novel features which are characteristic of this invention are pointed out in the claims, the invention will be better understood by referring to the following description, taken in connection with the accompanying drawing in which a specific embodiment has been set forth for purposes of illustration,

In the drawings the figure is a schematic diagram of a relay circuit embodying the inventlon.

1n the figure, a double triode tube 29 operates as a coincidental keytube which develops a series oi voltage pulses in the plate resistor oi the first section of double triode tube 3d, operating as an amplifier. The plate oi the second section oi tube is is coupled by a gaseous conduction tube ti'to the grid of the first triode of a tube .59 the first section of which operates as e D. C. amplifier to operate a relay, and the second section or which is used to maintain constancy oi current drain from the power supply source.

A battery "It with the negative end grounded and connected to ground line It has its positive end connected to the negative end oi battery 1!,

2 and to cathode line Ii. The battery "H has its positive end connected to plate supply line 14. Between lines 13 and 12 are connected in series the ballast resistor 15 and the filaments oi the three tubes 20, I0 and B9.

The tube 2|! includes two triode units with common cathodes 21, two grids 22 and 23, and two plates 21 and 25. Tubes 30 and are of similar construction with cathode 3i and Si, grids -82, I3 and b2, 53, and plates 34, 35 and 59, respectively. The cathodes of all tubes are connected to line It. Input to the system is from terminals it, ii and i2, oi which terminal i2 is connected to ground line 12. Terminal i0 is connected through condenser l3 to the grid 22 of tube 29, which in turn is connected through resistor is to cathode line 13. Similarly terminal ll l-s'connected through condenser H to the grid 23 ct tube 20 which in turn is connected through resistor It to the cathode line ll.

It is assumed that negative voltage pulses are impressed irom two separate channels between terminals it and i2, and between terminals ii and it respectively by a pulse circuit such for example as shown in my copending application above identified. The plates it and 2d are connected together, and through resistor 28 to the plate supply line "it, also through resistor ll to the grid 32 ct tube to, which in turn is connected through resistor 28 to the ground line 112. The plate 96 or tube to which is under control oi grid 32 is connected through rvnzictor so to plate supply line it, also through condenser ll to grid so of tube at, which in turn is connected through resistor lit and through condenser lid to cathode line it. The plots 35) oil tube to, under control of the grid 33, is connected through resistor it to the plate sup ply line it, also-to one terminal or a two ter 7 minal gaseous discharge type device M such as e. neon lamp or a voltage regulator tube. The other terminal oi" the device M is connected through resistor 62 and condenser it to the ground line l2, and also through resistor M to the grid 52 oi the tube 50. It will be understood that the device ll will normally insulate the plate 35 irom grid 52 and will conduct only durinc; portions of the time when the system is operative.

The plate 99 under control of grid 52 is connected through the winding I56 of a relay 5'! to the plate supply line It. This relay is provided with an armature which normally is held away from the pole oi the relay, but which is drawn to the pole when suitable direct current flows tion of overlap through winding 58. connected to the armature and to a front contact for operating a work circuit not when the armature is pulled down toward the pole piece.

The plate 54 is also connected through resistor 60 to the grid 53, which in turn is connected through resistor 6i to ground line H2. The plate 55 under control of grid 53 is connected through resistor 62 to the plate supply line '14.

The constants of the system are so chosen that in the absence of signal inputs at terminals 50 to l2, a large voltage drop occurs in resistor 26, and the first section of tube 33 is biased far below cutoff so that no 35, but that when signals are simultaneously impressed on the grids 22 and 23 making them both sufliciently negative to prevent current flow to the plates 24 and 25, the grid 32 comes to cathode potential so that current passes through resistor 38. Therefore a negative voltage pulse occurs at the plate 34 corresponding to the dura of the input pulses at the teriil to i This pulse is transmitted through condenser 31, and by the action of resistor 38 and condenser 39 produces a negative pulse of saw tooth nature on the grid 33. Since in the absence of such pulses the grid 33 is at cathode potential, a. large current flows through plate resistor 40, so that the potential of the plate 35 is low, and the voltage across device M is insufflcient to cause gaseous conduction. With the circuit operative, the potential of the plate 35 increases to a high value and returns to the normal value at the pulse recurrent rate. The device ill fires and extinguishes at the pulse rate so that current flowing from plate supply line 74, through resistor 40, and device 4! to resistor 42 and condenser 33 in a short time builds up a positive voltage across condenser 43, raising the negative terminal of 4! to above the potential of the cathode line 73. By use of resistor :14, the grid 52 is maintained at cathode potential although there may be some ripple across condenser 43 at the pulse recurrence rate. As a result, relay winding 58 passes current, and the armature closes contacts 58 and 59. When the pulses on the grid 33 cease, a steady state is brought about with device 4| not conducting, whereby the current in relay winding 56 drops and the relay contacts are opened. 4

In radio control devices it is sometimes helpful to maintain the plate supply substantially constant regardless of the operation of the relay. For this purpose, the resistors.

current fiows in resistor pressed on the grid 53. decreasing the current in resistor 82. It will be understood the normal current through relay winding 58 and resistors 60 and BI will be much quired to operate the relay 5]. By suitable design the current from the battery H is made substantially independent of the amount of relay cur rent.

It will he noted that in the above system the control of the relay is positive in response to incoming coincidental signals. The coupling systern including the tube 3| may, however, be applied to other uses where similar operating characteristics are required. The constant current features may also he applied to other circuits to maintain a substantially constant drain on. the plate source.

Although a specific embodiment has been shown for purposes illustration, various changes and adaptations a he made therein as will be apparent to a person skilled in the art. The invention is only to limited in accordance with the scope or the following claims.

I claim as my invention:

1. A constant current circuit comprising a pair of space discharge devices having anodes and control elements, a source oi anode current connected to supply said anodes, a load connected in series with the anode of one of said devices, signal means to cause a change in the amount of current passing through said load. and a direct coupling between said anode of said one device and the control element of the other of said devices connected to cause the space current of said their device to vary inversely as the space space current of said stant load is maintained on said source. ELLISON S. PURINGTON.

REFERENCES CITED The following referenlces are of record in the file 01' this patent:

UNITED STATES PATENTS Number 

